The nucleoside-modified messenger RNA in COVID-19 mRNA vaccine BNT162b2 is formulated in lipid nanoparticles, which enable delivery of the RNA into host cells to allow expression of the SARSCoV-2 S antigen.
The vaccine elicits both neutralizing antibody and cellular immune responses to the spike ( S ) antigen, which may contribute to protection against COVID-19 disease.
Efficacy in participants 16 years of age and older
The efficacy of COVID-19 mRNA vaccine BNT162b2 was evaluated in participants 16 years of age and older in two clinical studies conducted in the United States, Europe, Turkey, South Africa and South America.
Study 1 enrolled 60 participants, 18 through 55 years of age. Study 2 is a multicentre, placebo-controlled efficacy study in participants 12 years of age and older.
Randomisation was stratified by age: 12 through 15 years of age, 16 through 55 years of age, or 56 years of age and older, with a minimum of 40% of participants in the greater than or equal to 56-year stratum.
The study excluded participants who were immunocompromised and those who had previous clinical or microbiological diagnosis of COVID-19 disease.
Participants with pre-existing stable disease, defined as disease not requiring significant change in therapy or hospitalization for worsening disease during the 6 weeks before enrolment, were included as were participants with known stable infection with human immunodeficiency virus ( HIV ), hepatitis C virus ( HCV ) or hepatitis B virus ( HBV ).
There was no requirement for prophylactic use of Paracetamol or analgesics.
Influenza vaccines could be administered outside a window ± 14 days of the vaccine doses.
In study 2, approximately 44,000 participants 12 years of age and older were randomised equally and received 2 doses of COVID-19 mRNA vaccine or placebo with a planned interval of 21 days.
The efficacy analyses included participants that received their second vaccination within 19 to 42 days after their first vaccination.
Participants are planned to be followed for up to 24 months, for assessments of safety and efficacy against COVID-19 disease.
The population for the analysis of the primary efficacy endpoint included, 36,621 participants 12 years of age and older ( 18,242 in the COVID-19 mRNA vaccine group and 18,379 in the placebo group ) who did not have evidence of prior infection with SARS-CoV-2 through 7 days after the second dose.
Demographic characteristics were generally similar with regard to age, gender, race and ethnicity among participants who received COVID-19 mRNA BNT162b2 vaccine and those who received placebo. Overall, among the participants who received COVID-19 mRNA vaccine, 51.1% were male and 48.9% were female, 82.8% were White, 8.9% were Black or African American, 26.8% were Hispanic/Latino, 4.5% were Asian and 0.6% were Native American/Alaskan native. 57.2% were aged 16-55 years, 42.6% were aged more than 55 years and 21.8% were greater than or equal to 65 years.
Efficacy against COVID-19 disease
At the time of the analysis of study 2, information presented is based on participants 16 years and older.
Participants had been followed for symptomatic COVID-19 disease for at least 2,214 person-years for the COVID-19 mRNA vaccine and at least 2,222 person-years in the placebo group.
There were 8 confirmed COVID-19 cases identified in the COVID-19 mRNA vaccine group and 162 cases in the placebo group, respectively.
In this analysis, compared to placebo, efficacy of COVID-19 mRNA vaccine BNT162b2 from first COVID-19 occurrence from 7 days after dose 2 in participants without evidence of prior infection with SARS-CoV-2 was 95.0% ( 95% credible interval of 90.3% to 97.6% ).
In participants 65 years of age and older and 75 years of age and older without evidence of prior infections with SARS-CoV-2, efficacy of COVID-19 mRNA vaccine BNT162b2 was 94.7% ( two-sided 95% confidence interval of 66.7% to 99.9% ) and 100% ( two-sided 95% confidence interval of -13.1% to 100.0% ) respectively.
In a separate analysis, compared to placebo, efficacy of COVID-19 mRNA vaccine from first COVID-19 occurrence from 7 days after dose 2 in participants with or without evidence of prior infection with SARS-CoV-2 was 94.6% ( 95% credible interval of 89.9% to 97.3% ).
There were no meaningful clinical differences in overall vaccine efficacy in participants who were at risk of severe COVID-19 disease including those with one or more comorbidities that increase the risk of severe COVID-19 disease ( e.g. asthma, BMI 30 kg/m2 or more, chronic pulmonary disease, diabetes mellitus, hypertension ). ( Xagena )
Source: MHRA - Medicines and Healthcare products Regulatory Agency, 2020